Thank you very much for this dedicated comment. I am glad that such a reaction is coming.
It is not easy to deal with the situation. It is one thing to remember one's teenage years, quite another to find a position as a parent. I myself work with young adults in the social field and I am aware that most of these resistances have an honest and serious background. The fact that my son warned me in advance and that I don't have to learn about his absence from the school first is very valuable, I agree with you. My son and I have a very good relationship, although it is extremely difficult to have a relaxed conversation with him, in which he also listens to my point of view.

A good citizen, in my view, is someone who maintains a good balance between serving the community and always encourages himself to become aware that life is development and that one can be confrontational in life without becoming a nuisance to others. Someone who claims ethical values for himself and thinks to live by them.

Yes, you are right, he should make up for the missed school material. I have now decided to make a telephone call with the teacher and inform her where my son is at the moment. I think it is always good to be pro-active and not wait for others to react. It took me some time, this article and your answer helped me. Thank you very much for that!